The present invention relates to the purification of gases, and more particularly to a method of purifying flue gases which contain noxious gases such as SO2.
Dry sorbent injection (DSI) has been used with a variety of sorbents to remove SOx and other gases from flue gas. However, DSI has typically been done in the past at temperatures much lower than 400° F. because equipment material, such as baghouse media, cannot withstand higher temperatures. Additionally, many sorbent materials sinter or melt at temperatures near or greater than 400° F., which makes them less effective at removing gases. The reactions products of many sorbent materials also adhere to equipment and ducts at higher temperatures, which requires frequent cleaning of the process equipment. To operate at these lower temperatures, the combustion gases must often be cooled before the sorbent was injected. This is an undesirable extra process step.
Thus, there is a need for a sorbent injection method that is effective at removing SOx gases at elevated temperatures.